Question

At ${100}^{o}C$, resistance of a conducting coil is $4.2\Omega$. If the temperature coefficient of resistance is ${0.004}^{o}C$, what will be the resistance of $0^{o}C$? (in ohm)

• A. 3
• B. 5
• C. 4
• D. 3.5

Answer 1

The correct option is A 3

Given,

$R_T=4.2ohm$

$T={100}^{0}C$

$\alpha =0.004{/}^{0}C$

$T_0=0^{0}C$

$\Delta T=T-T_0=100-0={100}^{0}C$

The resistance, $R_T=R_0(1+\alpha \Delta T)$

$R_0=\frac{R_T}{(1+\alpha \Delta T)}$

$R_0=\frac{4.2}{(1+0.004\times 100)}=3\Omega$

The correct option is A.